1. Field of the Invention
The present invention relates to an ink-jet printer that ejects droplets of ink onto a recording medium and a method of controlling an ink-jet printer.
2. Discussion of Related Art
An ink-jet recording head having a plurality of ink ejection nozzles and a plurality of pressure chambers communicating with the nozzles, respectively, may have a problem that air bubbles and deteriorated ink remain in the nozzles and/or the pressure chambers and accordingly an ink-ejection performance of the recording head lowers. To solve this problem, it is needed to carry out a purging operation to purge the recording head of the air bubbles and the deteriorated ink. For example, Japanese Patent Application Publication No. 2004-58348 or its corresponding U.S. Patent Application Publication No. 2004/0196326A1 discloses an ink-jet printer that includes an ink-jet recording head; an ink tank that stores ink to be supplied to the recording head; an air tank that stores air having a predetermined pressure; and an air pump that supplies the air to the air tank, and that carries out a purging operation. When the ink-jet printer carries out the purging operation, first, in a state in which an air valve that is provided between the air tank and the ink tank is closed, the air is supplied from the air pump to the air tank, so that the air pressure in the air tank is increased up to the predetermined value. Then, when the air valve is opened, the air in the air tank (i.e., the pressurized air) instantaneously is supplied to the ink tank. Consequently the air pressure in the ink tank is increased up and the ink is quickly supplied to the recording head. Since the ink is quickly supplied to the recording head, the air bubbles and the deteriorated ink remaining in the recording head are forcedly discharged from the nozzles thereof